Method of oxidizing steel or iron sheets.



Patented M APPLICATION FILED NOV. 8, 1912.

i all when@ it may concern:

l Application led.Novemlier 8, 1912. .Serial No. 130,126.

UNiTED 'STATES PATENT 'onirica i, JOHN E. 'cAnNAHAN A Np-AR'ri-ivnc.MASKREY, orf-carmen, omo.

vini'rlon or QXIDI'ZIG STEEL on IRON Simms.

- sneotcation of Letters Patent. Patented Mar. 18,1913.

-Be'it known that 'Wa-JOHN E.A CARN'AHAN' and ARTHUR J. MAs'KREY, bothcitizensof the United States, aritlboth residing at'Canton, lin thecounty of Stark `and State of Ohio, `have invented a newv and usefulMethodof ,.Oxidizing Steeler .Iron Sheets, of which the followingis aspecification.

`. (The-.invention relates -to 'the oxidation-'of the surfaces of steelor iron sheets,- for the purposel of givin them a uniform bluish color,and especia ly to'that method of bluing -whereby vthe sheets are. heated1n^an annealing box and .wherein steam is'- em.

ploy'ed as lin-'oxidizing agent.

. 'A well known method of oxidizing very. chea .grade of steel',`sheets, Vas for use 1nmaking ordinary stove.' ipes, is to heat them in`an annealing box an blue them vby a bath of steam immediately fafterthe sheets come "from thereducing rolls, 'and before the 4`sheets havebeen ,",Ipickled yor otherwise Aff'zleansed, and then tosubsequentlyanneal I Jthesheets and finish them `between cold rolls;

fbut it is obvious that theunclean condition j ofthe sheets beforeltheyr are pickled andthe anneal and cold roll the sheets, and t en toheat them-in anannealing boxjand blue' them with' a bath' of steam;'butit' is obvious that the smcothing'and' polishing of, the surface bythepressure of the cold rolls',

and the close contact 'of the surfaces of the A finished sheets .when`packed for annealing, prevents thefdevelopment of a.v deep anduniformoxidation on the surfaces, and does' 'not give therich color`which. is muchdepresent inventi'omin the practice. of which. ythe blacksheets are first pickled and .then

sired. .These diiiculties are overcome by the i packed in apile andannealedI in theilsual manner; and then cooledand separated and repackedfand reheated inan annealing box,-

`and-then oxidized by steam' When? partially cooled, after lwhich theyarec'oldrolledv for finishing, Vandvagain heated yfor softening and`steamed for .preserving .the uniform color, after] which theym'ay beagain cold rolled for certain special uses.

`.., T1he i1vention. thus set .forthf "general 'terms-1s preferablypractised by the'us'e of an ordinary annealingpan and boa, as illus-'trated in the accompanyingdrawingform.-

ing part hereof, in Which- Figure 1, is aside elevation of anannealing'pan and box, with part. of the box broken away to show a pileof sheets packed therein; Fig. 2, a cross 'section of the annealingpanand box', on a track androller truck,

showing a pile of annealed sheets packed therein; Fig.. 3, a similarsection showing .a pile o'f sheets loosely repacked therein, foi' j theimproved bluing process.. Fi .4, af'rag- .mentary View of the surface oa pickled unfinished sheet showing the comparativel f rough andconvoluted condition thereo and Fig. 5, a fragmentary exaggeratedsection of a pile of repacked uninished annealed sheets, showing theslight interval .between the rough and convoluted surfaces thereof. A l

Similar numerals refer. to similar parts throughout'the drawings. f

For the purposes fof the present process, when ythe black'sheets'havebeen reduced by rolling, they are first'pickled Vin sulfuric ormuriaticacid and'then'washed. in clear Water in the usual manner, for completelycleaning the surfaces thereof, which then presents a rou-ghened and'somewhat porous condition', as illustrated in Fig. 4. f The sheets'.are then packed'in'a' pile 1, on an annealing pan 2 and thencoveredwithan annealing' box 3, the rim of which lated with sand 4.- in .the lusualmanner, to seal the box. The sheets arejthen annealed by dieating themin. 'a furnace to some 15000 F., fora substantial period, andare thencooled by With-1 drawing' them .from the furnace, while covered by thebox, in the usual manner.

The' high heat( ofthe annealing process andthe softening iniuencethereof, causes the sheetsof the pile to subside and to packand stick soclosely together. as to substantially ,exclude the entrance of air orsteam.

between them.,' v'1 `hi s.adhesion ofthe sheets together 1s 'sotenacious, that it requires eon-V siderable .forceto separate one sheetfrom another, and no doubtthe principal reason Why sheets have notvheretofore been oxidize'd immediately after being pickled and annealed.

i When: the "shee`ts are` cooled after being'v annealed, the boxis-removed and the sheets..

' are first separated and then re acked one by one, the order of thesheets veing preferably reversed to avoid a'contacting of .the

same sides in the repacked pile; and itis evident that the rough andporous condition of the unfinished surfaces of the sheets, together withthe slight distortion in lshape caused by their separation, preventsthem from being repacked so closely together as to exclude air or steamfrom between them. i' I=`1ct, it ha.-y been found that the separatingand repacking ot the sheets as described, will leave such a substantialinterval between them as to permit a free entrance of steam between themand cause a. complete and uniform oxidation of the adjacent snrfaees.The. sheets are again covered by an annealing box, the rim of whichluted by .sand as before` and the repacked sheets are then heated in afurnace to a dull red heat or about 1000@` l".` after which they arewithdrawn from the furnace and cooled while yet covered by the box, to adark red heat: whereupon dry live steamris. introduced into the box,which in practice is done by slightly elevating one end ofthe box andinserting thcrennde a nozzle through which steam is discharged into thebox, the luting sand being packed around the nozzle. The bath of steamis preferably maintained until the sheets are so cooled that the. steamwill not be further decomposed, after which the box is removed and thesheets are smoothed or polished by passing them a sufficient. number oftimes between the cold rolls to produce the finish desired.

lt has been found that by separating and repacking thc previouslypickled annealed sheets, and blning them by a bath of steam before theyhave been smoothed or polished by cold rolling, a very. deep, andsubstantially `complete and uniform oxidation of the surface isattained: which is no ldoubt caused by the factY thatthe separation andrepacking of the sheets. permits the steam to enter freely between them,and the roughness of the unfinished surfaces, permits the steam topentrate more deeply into the body iof the sheet than would be possibleif the same had been previously smoothed. Furthermore the lower degreeof heat required for the bluing, does not cause the sheets to pack soclosely together as in the annealing process. The subsequent coldVrolling of the sheets for finishing the surfaces. serves to impress thedeep oxidation thus formed into` the surface of the sheet, so that theoxida#` tion is not'. merely a superficial film, but has adeep'interengagementwith the body of the sheet. Tty is preferred to givethe sheets an odd number of passes between the cold rolls, thereby againreversing' the order of the sheets in the pack for the subsequent stepin the process.

Thqamount of cold rolling necessary for finishing the more highlypolished sheets and impressing the oxidation therein, usually makes thcsheets too hard forgencomparatively soft condition of the sheets afterthe rcheating permits a finer `gloss to be obtained b v the final coldrolling. Furthermore, the rcarrangement of the pack to bring the sheetswhich were at the bottom of? the pack for the first steaming n'ocess, tothe top of the pack for the seeonil steaming process. relieves thesesheets from the superimpesed weight of the pack, and permits` the steamto fl'ow more freely between them: and it is evident that if thesesheetsare not uniformly and deeplyoxidized by the first steaming, theyvwill be so oxidized by the second steaming. By these means, a deeperand more tenacious oxidation is produced on the surfaces of the sheets,and while `it may not be possible to produce an absolutely uniform colorfrom the middle portions to the edges of the sheets by any method ofoxidizing them'while cooling in packs, it is believed that a greateruniformity of color is attaiired by the method herein set forth, than byany other process of the same character. Thatevcr variation in colorwhich may result from this method, is a gradual, uniform and undefinedchange from the middle portion to the edge portion, Without showing anywell defined or distinct-ive zeges or bands of color on the surfaces oft-lie\sheets.

Te claim 1. The method of oxidizing steel or iron sheets whichconsistsin pickling and annealing them. then .separating and repacking them inreverse order, then oxidizing them by heating and steaming them in anannealing box, then cold rolling them, then repacking them in reverseorder and repeatin; r the oxidizing process, and finally cold rollingthe sheets.

2. 'lhe method of oxidizing steel or iron sheets which consists inpickling and anneal- \in-g them, then separating and repacking :them inreverse order, then oxidizing them by heating and steaming them in anannealing box, then cold rolling them, and then repacking them inreverse order and repeat-ing the oxidizing process.

The method of oxidizing steel or iron sheets which consists in picklingand annealing them, then cooling, separating and repacking them one hyone, :hen oxidizing them bv heating and steaminer in an annealprocess.

'- e`ss, and finally cold rolling the sheets.

el. The method of oxidizing steel or iron sheets Which consists inpickling'and annealing them, then cooling, sept ating and repacking themone byone, then oxidizing them. by heating and steaming .in `einannealing box, then cold rolling them and then repacking them andrepeating the oxidizing 5. The method of'oxidizing steel or iron sheetswhich consists in pickling and anneah.

ingth'em, then separating andV repaeking them in reverse order, thenoxidizing them in :inA annealing box, then cold rolling them, thenrepaoking them in reverse order and repeating the oxidizing process, andfinally` cold rolling vthe sheets.

(l.v The method of oxidizing steel or ir'on sheets which consists inpiekling and annealing them, then separating land repacking them inreverse order, then oxidizing them in an annealing box, then coldrolling them, and then repacking them in reverse order and repeating theoxidizing process.'

. 7. The method of oxidizing steel lor iron sheets which consists inpickling and annealing them, then cooling, separating and repaeking themone by one, then oxidizing them in an annezilingbox, then cold rollingthem, then repaeking them andrepeating the oxidizing process and finallycold rolling the sheets.

8.l The method of oxidizing iron orsteel sheets which consists inpieklingandanneal-A ing them, then cooling, separating and repackingthem one by one, 'then oxidizing` them in an annealing' box, then coldrolling them, and then repacking them and'repeat# ing the oxidizingprocess.

9. The method of oxidizing steel or iron sheets which consists inpiekling and annealing them, then' cooling. and separating the sheetsone troni another and oxidizing;l them in nn annealing box, then coldrollingtheim' then repeating the' oxidizing process, and finali)v coldrolling the sheets.

10. The method ot' oxidizing steel or iron sheets `which consists inpickling and annealingthem, then cooling! und separating the sheets onefrom another and oxidizing them in an annealing box, and thencohlrolling` them, then repeating the oxidizing process.

JOHN E. CARNAHAN.

ARTHUR J. MASKREY,

"'itnesses z Flinn J. Zn'r'rnnn, llLrnncDi SCHMIDT.

